Plant growth regulants

ABSTRACT

Combatting weeds by applying thereto one or more substituted benzophenone.

Yamadla et a1.

PLANT GROWTH-11 REGULANTS Nippon Kayaku Kalbushiki Kaisha, Tokyo, Japan Filed: Aug. 21, 1972 Appl. No: 282,270

Assignee:

Foreign Application Priority Data Aug. 24, 1971 Japan 46-64658 US. Cl. 71/123 int. Ci A01 9/24 [58] Fieid 01' Search 71/123 [56] References Cited UNITED STATES PATENTS Primary Examiner-James 0. Thomas, Jr. Attorney, Agent, or Firm-Russell & Nields [57] ABSTRACT Combatting weeds by applying thereto one or more substituted benzophenone.

3 Claims, N0 Drawings PLANT GROWTH REGULANTS DETAILED DESCRIPTION OF THE INVENTION Our extensive investigation on novel plant growth regulants have now led to the finding that compounds having the general formula (1);

wherein R, and R which may be the same or different, each represent hydrogen atoms or lower alkyl groups, R is a lower alkyl group or a chlorine atom and R is a lower alkyl group or an allyl group, have excellent plant growth regulatory properties, for example, effective for inhibiting seed germination, root elongation and plant (including algae) growth. This invention has been accomplished on the basis of the above finding.

Representative examples of compounds having the general formula (1) which are used as active ingredients in the plant growth regulants of this invention are as follows:

l. 2,2-dimethyl-4-methoxybenzophenone,

b.p. 140 142C/2mmHg 2. 2,3'-dimethyl-4-methoxybenzophenone,

b.p. 162.5- 164.5C/2.5mmHg 3. 2,4-dimethyl-4-methoxybenzophenone,

b.p. 160 161C/l5mmHg 4. 3-chloro-3'-methyl-4-methoxybenzophenone,

m.p'. 102- 102.5C

,5. 3,3-dimethyl-4-methoxybenzophenone,

m.p. 62 65C 6. 3,3-dimethyl-4-ethoxybenzophenone,

m.p. 51 53C 7. 3-sec.-butyl-3-methyl-4-methoxybenzophenone,

b.p. l82- 183C/2mmHg 8. 3-isopropyl-3-methyl-4-methoxybenzophenone,

b.p. l75- 176C/2mmHg 9. 3,3-dimethyl-4-n.-propoxybenzophenone,

b.p. 17l- 172C/2mmHg l0. 3,3'-dimethyl-4-a]lyloxybenzophenone,

b.p. l77 178C/2mmHg 1 l. 2,3',4'-trimethyl-4-methoxybenzophenone,

b.p. 168 169C/2.5mmHg l2. 3,3',5-trimethyl-4-sec.-butoxybenzophenone,

b.p. 170- 175C/1.5mmHg l3. 3-tert.-butyl-3 -methyl-4-methoxybenzophenone, m.p. l.5 102.5C

14. 2,3-dimethyl-4-methoxybenzophenone,

m.p. 70 71.5C

l5. 3,4-dimethyl-4-methoxybenzophenone,

m.p. 75 76C 16. 3,3,5-trimethyl-4-methoxybenzophenone,

m.p. 85 86C 17. 2'-methyl-3-chloro-4-methoxybenzophenone,

m.p. l05 106C 18. 2,3-dimethyl-4-ethoxybenzophenone. b.p. l80 l8l.5C/3.5mmHg Q cox 19. 2.3'-dimethyl-4-sec.-butoxybenzophenone.

b.p. l- 186C/3mmHg 20. 3-methyl-4-methoxybenzophenone,

m.p. 79.5 805C 21. 2-methyl-4-methoxybenzophenone,

m.p. l47- 148C/0.5mmHg 22. 3-chloro-4-methyl-4-methoxybenzophenone,

m.p. 107 108C 23. 2,3 ',5-trimethyl-4-methoxygenzophenone,

b.p. 168 170C/2mmHg 24. 3,3 ',4-trimethyl-4-methoxybenzophenone,

m.p. 98.5 99.5C 25. 3-methyl-4-methoxy-4-ethylbenzophenone b.p. 176 177C/lmmHg 26. 3-methyl-4-methoxy-4-n-butylbenzophenone b.p. 213 215C/2mmI-Ig 27. 3-methyl-4-methoxy-3-n-propylbenzophenone b.p. l87.5 l89.5C/2mmHg Some of the compounds of this invention, for example, compound Nos. 4, 17, 20 and 21 are known compounds but have not yet been found to have any plant growth regulatory actions. These and other compounds of the invention may be prepared according to the socalled Friedel-Crafts reaction, usually in the presence I of a solvent, as illustrated by the following reaction scheme:

Wifiii X represent halogen atom and R to R have the same meanings as defined above. Thus, for example, a Friedel-Crafts catalyst is first added to a compound of the general formula (111). Effective Friedel- Crafts catalysts include aluminum chloride, zinc cloride, ferric chloride, stannic chloride and titanium trichloride. The catalyst is used preferably in an equimolar to ca. 5% molar excess amount to the compound of the general formula (11) used. The use of a larger amount of the catalyst are not preferred since it may acceralate the cleavage of ether bonds present in compounds of the general formula (III) or (I). Subsequently, a compound of the general formula (11) is added dropwise. The compound of the general formula (II) is used preferably in an amount at most equimolar but in most cases ca. 5% lesser than equimolar. The reaction may be made to proceed more smoothly by using an inert solvent such as an aromatic or aliphatic hydrocarbon, carbon disulfide, nitroalkane or a chlorinated hydrocarbon solvent. When the compound of the general formula (II) is used in an amount approximately one half the amount of the compound of the general formula (III), the compound of the general formula (111) per se functions conveniently as a reaction medium. A temperature at which the compound of the general formula (II) is added dropwise is preferably within the range of from 0C to 30C. Simultaneously with the addition, the reaction takes place with hydrogen chloride being evolved. After the addition, the reaction temperature is raised and the reaction is continued until evolution of the hydrogen chloride is ceased.

The reaction is completed usually in 2 to 5 hours. The

reaction mixture is then cooled and poured into icewater containing hydrochloric acid. and the separated product is isolated and purified in a conventional man- Other compounds of the invention can be synthener to obtain the desired product. In a somewhat modisized in almost the same manner. tied manner, a compound of the general formula (11) is For actual use of the compounds of the invention as admixed with acompound of the general f rm la (111) active ingredients in the plant growth regulant, they and a catalyst is added to the resulting mixture. This 5 y be used as Such or in admixture with asultuble process i i i i p f d h Stannic id rier material to form emulsifiable concentrates, wettai d as h cataiysL ble powders, dusts, granules or tablets.

B l w i an example f Synthesis f h Compounds The application rate of the active ingredients of the f thi i nti invention may vary usually from g to 100 g per are.

I I I 10 preferably from 20 g to 80 g per are, although it de- Synthesis of 3,3 -dimethyl-4-methoxybenzophenone pends of Course upon the type of the area to be 13.3 Grams (0.1 mole) of aluminum chloride is .treated, the weed to be controlled, the particular active added in small portions to a mixture of 18.3 g (0.15 ingredient used and the like. The term carrier matemole) of o-methylanisole and 20 ml of benzene at a rial" is used herein to mean a vehicle or an extending temperature not higher than 30C. After the addition, agent with which the active ingredient is brought into 15.5 g (0.1 mole) of m-toluyl chloride is added dropcontact with plants. Illustrative of solid carrier materiwise to the mixture over minutes while maintaining als are clays. kaolin, talc, diatomaceous earth, silica the temperature at or below 10C. During this addition. and calcium carbonate. lllustrative of liquid carrier maa violent exothermic reaction takes place with hydroterials are benzene, alcohols, acetone, xylenes, methylgen cloride being evolved. Thereafter, the reaction is naphthalenes, eyclohexanone, dimethylformamide, di continued at a tempratum not higher than for 2 methylsulfoxide, animal and vegetable oils, fatty acids hours to give the reaction mixture which is a red and esters thereof andvarious surface active agents. cous liquid. The reaction is further continued by keep- Th plant growth regulatory action may f th b@ lhg the mixture 3125010 for 1 hourwhen the sured by jointly using a suitable conventional adjuvant sulting reaction mixture is poured into a mixture of h as a spreader, l if i agent, wetting agent water (100 ml) and ice (100 g) containing a small d i i agent amount ofconcentrated hydrochloric acid, the mixture The active Compounds of the invention may be used d.eCOmpOsed.Wl.th evolution of heat ,whereby,an together with other herbicides such as 2-methylthioganic substance 18 separated out. This organic sub- 4, bisisopmpylamino s triazine (Pmmetryne). stance is then extracted with 50 m1 of benzene and the methymhio 4(ybisethylamino s triazine (simelryne) extract 15 washed twice with 5% sodium hydroxide and S (4 ChlOmbenZy] N NdietMhMocarbame (Saturn) then with water, dried over anhydrous sodium sulfate iSOpmpyl N (3 chlorbphenyl)carbamate (chlomi and concentrated in vacuo to give 23.3 g (crude yield WC) Bbcnzenesmfonvlamidoethvl) O O- a Crude. fil g g s diisopropyldithiophosphate and the like. ln particular, 15 t en lze mm m 0 l am to satisfactory results are achieved when the compound of give 2 1 g j 895%) Ofa white crystallme product this invention is used in combination with the last meng i' gi ii' tioned S-(B-benzenesulfonylamidoethyl) 0,0-

y diisopropyldithiophosphate.

Found 1 c 80.20%; H 6.70% 40 Calculated: C 79.97%; H 6.71% The active ingredients of the invention may also be In the following Table 1 are shown several examples used in admixture with other agricultural bactricides. of synthesis of the same compound wherein the sorts of insecticides, nematocides, soil improvers, fertilizers catalyst and solvent are changed. and the like.

Table 1 Examples of synthesis of 3,3-dimethyl-4-methoxybenzophenone Temperatures Amount of Solvent Catalyst (C) at which Reaction Compound Amount Amount Compound (11) conditions Yield of (111) used used used is added Temper- Time Com ound (mol) Compound (ml) Compound (mol) dropwise ature (C) (hrs) (1) (l) 2.0 AICL, 1.0 5 10 25 3.5 75.7 1.1 chlorobenzen 50 10 or less 25 3O 3 85.4 1.3 carbon disullide 400 5 25 2 78.7 1.1 benzene 5O 10 25 30 2 70.0 1.5 toluene 3O 5 7 room tem- 4.5 92.9

perature nitrobenzene 30 l 5 2.5 91.2 ortho-dichloro- 30 5 5 89.3

benzene 2.0 chlorobenzene 30 FeCl 2 3 2O 25 2 25 1 1.] carbon disulfide 450 ZnCl l5 20 5 72.1

22 2.5 1.5 1.2-dlchloro- 30 SnCl 5 or less 45 50 2 92.7

ethane TiCl 10 15 room tem- 2 95.7

perature Remarks:

" Amount of compound (111) used is expressed in term of mole per mole of compound (11). Yield of compound (I) is expressed in term of (crude yield) (purity).

Excellent plant growth regulatory action of the active compounds of the invention will be demonstrated by the following examples.

EXAMPLE 1 l. Pre-emergence field test with the whole soil surface treated immediately after crop seeds sowing but before emergence of weeds Each of l/5,000 are Wagner pots was charged with a given amount of a diluvian soil. A given number of [0 seeds of crabgrass (Digitaria SPP.) and pigweed (Amaranthus SPP.) both predominant weeds found in usual dry field farming. were sown thereon and covered with the soil to a depth of about 0.5 cm. On these pots were separately sown seeds per pot of each of soybean, cotton and sunflower and then covered with soil to a depth of 1.5 to 2 cm. Each liquid reagent diluted which with well water is scattered on the soil surface so that the active ingredient compound according to this invention may be 20, 40 and 80g per are respectively. 7 Herbicidal activities and the growth conditions of crope are observed on the thirty days after the treatment. The results of observation are shown in the Table 2. Paddy field: water application after the transplantation of paddy plant.

face of the soil and two young rice seadling at three leave stage were transplanted. The irrigation water was kept at the level of about 0.5 cm until germination of banyard grass was observed. After the germination, the irrigation water level was raised to about 3 cm. When banyard grass reached 1.5 leave stage (usually 10 days after the transplantation), the liquid reagent diluted with water was applied to the individual pots so that the active ingredient compound according to this invention may be 20. 40 and 80 g per are respectively.

During the test, the irrigation water level was kept at 3 cm. After the treatment for days, investigations were made for herbicidal action on barnyard glass and for presence or absence of influence on dry field crops Table 2 herbicidal Brien on Influence on dry Influence on Applicafield crops l tion rates crab barnyard soycotsunpaddy rice Tent compounds (g/are) grass pigweed grass been I ton flower lunts Compound of the invention 20 5 5 4.5

CH ca;

C CO 00a; 4 s 5 s (compound No. 5) 8O 5 v 5 5 CH CH C0 -O-CH3 (compound No. 2) 80 5 5 5 0 cu co o-tzi-i mpp 3) B0 3.5 4 4 Control c1 G 2 40 5 5 5 -H+ +H- H I 5 5 5 -H+ x x at (Trade name NIP) Rmarks:

numerals:

5: Completely killed 4: 80% killed Ratings of herbicidal effect, are defined in terms of the following SPP.) was superficially incorporated into the top sur- Table 2 Continued areas survived.

2) Ratings of injuring effect on crops are defined in term of the following symbols:

x: Completely killed H-H: Severe injury Medium injury Slight injury Extremely slight injury and the aquatic rice plants as the degree of the influence, if any. The results are shown in Table 2.

As is evident from Table 2. the active compounds of the invention have no influence upon the test crops. although the active compounds of the invention have extremely high safety in comparison with the control, they-have approximately the same herbicidal effect as that of the control.

The following examples illustrate some influences of No injury (Crops grew as in untreated areas.)

these seedling beds were poured ml per bed of each of the liquid compositions formulated in a manner such that the concentrations of the active compound of the invention might become, when applied, 500 and 100 ppm, respectively. Thereafter, 15 seeds of paddy plant,

the active compounds of the invention on a variety of plants.

EXAMPLE 2 Influence on a variety of plants In petri dishes of 9 cm diameter were placed sea sand to a depth of about 5 mm to provide seedling beds. Into Table 15 seeds of barnyard grass, seeds of manna-grass, 30 seeds of lucern, 20 seeds of tomato and 10 seeds of turnip were sown on individual petri dishes.

The assay was examined in an artificial climate chamber using light and darkness and temperature conditions alternating at 12 hour intervals; artificial illumination at 8,000 luxes (at the point of the petri dishes) and temperature of 25C for day time; no light (darkness) and temperature of 20C for night time.

After the treatment for 14 days, investigations were made with the respective test plants for their growth condition. The results are shown in Table 3.

Test plant rice plant barnyard grass c1-ub-grass lucern turnip lvumflbo Application mt (ppm) 500 500 100 500 100 500 100 500 100 500 100 Affected 'r '1' r r 'r '1 T 'r r 'r 'r r portions 0 C C C C C C C C C P C of P R n R R a 11 R n R n a ll 'l'estv compound 3 0.5 3 2-5 5 5 5 3-5 3 2.5 2 1 N 1 2.5 1 4.5 4.5 5 5 4 5.5 3.5 3 o 0 1 o 1 o 4 4 2 o o o o o 4 o o 1 0.5 1 o o 0 o o 0 o 1 0 1 o 4.5 4 0 o o o o o o o 4 3 5 5 1 0 0 o 0 o a 0 0 5 1 5 5 0 o 0 o 0 1 1 0.5 5 4 5 5 1 o o 0 o 1 Table 3 19 1555551 plant rice plant barnyard grass crab-grass lucern turnip tomato Application raies (pp 500 100 500 100 500 100 500 100 500 100 500 Affected 1' 1' 1 T '1 T 1' '1' 1 T '1' portions 0 c c c c c c c c c c of p B n R a R n I R 11 n n R No. 7 2 1 3 0 1 3 2 3.5 o 0 o o o o o 0 o o o o o o o 3 1 3 o 5 1 2.5 o o o o 3 1 2 1 5 5 3 1 3.5' o 1.5 s 1 o 2 2 5 5 o o 0 o O 4 1 3 1 5 5 4.5 1 4.5 o 3 2 o 1 o 4.5 3.5 1.5 1 1 o 1 9 1 o 2 o 5 0 o o o o o o o o o 5 5 1 0.5 o o 0 1o 0 o 1 o 5 5 1 0.5 o o 0 o o o 0 5 5 1.5 o o 0 o 2 o 2 1 4 3.5 2 0.5 2 1 1 11 1 o 1 0 5 5 1 o 0 o o 2 1 1 o 4.5 3 1.5 0.5 o o 1 12 1 o 2 0 5 3 o o 0 o o 0 o o o 4.5 1.5 4.5 1 1 0.5 o 13 o o 0 o o o o. o o o o 0 o o o 4.5 3.5 4.5 1.5 2 0.5 1

0.5 o 1 1 4 3 2 1 1 1 0.5 14 o o 2 2 4 1 o o o o o 2 o 1 1 5 3 1 o 1 o 0.5 15 0 0 3 1 5 4 o o 0 o o 3 o 3 1 5 4 1 o o o 1 1 o 0 o 4 3 2 2 1.5 o 1 5 16 0 o o o 5 4 o o o o o 1 o o o 4 o 2 2 1 0.5 0.5 17 o o o o 4.5 0 o o o o o 3 1 2 1 4 4 1 1 o o 1 1a 0 o- 3 3 4 2 2 1 o o o 3 1 2 o 4 3 2 1 o o o 19 0 o o o 4 3 1- 0 o o o 3 1 2 o 5 3 2 1 o o o 2 1 3 2 '4 3 2 1 o o 0 22 0 o o o o o o o o o o 3 2 3 2 4 3 3 2 o o o o o 1 o 4 3 3 2 1 1 1 23 o o o o o o o o o o o 1 o 1 o 4 3 4 2 1 1 1 2 1 2 1 4 4 2 1 1 1 1 24 o o o o 5 5 0 o o o 0 1 1 4 3 5 5 1 o o 0 0 25 0 0 5 4 5 5 o o o o o 1 1 5 4 5 5 1 o o o o 3 1 3 1 3 2 4 0 1 1 1 26 o o o o 0 o o o o o o 3 1 1 1 5 5 2 1 4 o 2 27 1 o 2 2 5 5 o o o o o Affected portions of plant:

T top portion; R root portion;

C chlorotic action The degree of growth inhibition at T and R was defined in term of the following numerical ratings:

5: Complete inhibition (Plants were completely killed or no roots appeared) 4: 80 76 inhibition No inhibition (Plants grew as in untreated areas) Ratings of chlorotic action (C) was taken on a. scale as defined below.

: All the test plants completely chlorotic 4: 8O 75 chlorotic 0: None chlorotic Example 3 Herbicidal action and rice plant injuring action of a. mixture of sulfonylemidoethyl) 0,0-diisopropyldithiophosphate (referred. to hereinafter as compound A) Weed inhibition test in rice cultivation (in paddy field) Treatment of under flooded conditions weeds) (pre-emergent treatment for EXAMPLE 3 Herbicidal action and rice plant injuring action of a mixture of 3,3-dimethyl-4-methoxybenzophenone (compound No. 5) and S-(,B-benzenesulfonylamidoethyl) 0,0-diisopropyldithiophosphate (referred to hereinafter as compound A) Weed inhibition test in rice cultivation (in paddy field) 1. Treatment of under flooded conditions (preemergent treatment for weeds) a. Test weeds barnyard grass, monochoria, toothcup, false pimpernel, flat sedge, water starwort and needle spikerush. b. Procedure for treatment with plant growth regulant compositions s A wettable powder containing Compound N0. 5 and Compound A as the active ingredients was diluted with water and then used for the treatment c. Test method Each of l/5,0()0 are Wagner pots was charged with the surface soil from the paddy field where a lot of the above-described test weeds had appeared in the last year. to provide paddy field conditions. The flooded water was kept at the level of 3 cm. A given amount of the composition to be tested was applicated under flooded conditions. After the treatment for two days 2 bundles (2 seedlings per bundle) per pot of paddy rice seedlings at 2.5 and 3.5 leaves stages were transplanted 2 cm deep from the top soil surface. After cultivation c. Test method Each of l/5,000 are Wagner pots was charged with the surface soil from the same paddy field as in t l to provide paddy field conditions while keeping the irrigain a glass greenhouse at 15 20C for 30 days 5 tion water at the level of 2 cm. Given doses of several lnVeIigati0nS Were made on herblcldal effects plant growth regulant compositions were then added f j y dropwise uniformly to the surface of the irrigation Ratmgs of herblcldal f y and Chemlgi] Injury water and admixed well with the surface layer soil of 3 The number of the survwmg test weeds l? each of cm in depth. After the treatment for 2 days, 2 bundles the treated and untreated areas (Classified numl ber of surviving test weeds in Table 4) was counted and the individual numbers so counted were summed to give the total number of surviving test weeds in the treated and untreated areas (Total number of surviving test weeds in Table I5 4). Ratings were given in terms of ratios of the total number of surviving test weeds in the treated areas to the total number. standardized as I00, of the test weeds which grew in untreated (2 seedlings per bundle) per pot of aquatic rice seedlings at 2.5 leaves and 3.5 leaves stages were transplanted. After cultivation in a glass greenhouse at 15 25C for 30 days, investigations were made for herbicidal effects and injury against rice. I

d. Ratings of herbicidal effects and injury against rice The same ratings were used as those used in the treatment under irrigation prior to transplanta tion of rice. I l

20 Test results are tabulated in Table 5.

areas.

Table 4 Herbicidal activity Injury a ainst t rice p ant Dose (g/a) of Dose (g/a) of Classified number of surviving Total number Ratio to total compound No.5 compound A test weeds of surviving number oftest 2.5 leaves 3.5 leaves barnyard Broad-leaf Needle test weeds weeds grown in stage stage grass weeds spikerush untreated area 5 3 5 l3 6 l0 0 0 O 0 0 5 O 0 O O 0 1 Untreated I0] 83 20 203 I00 Table 5 Herbicidal activity Injury ayainst Dose (g/a) of Dose (g/a) of Number of surviving weeds Total surviving weeds rice p ant compound No. 5 compound A barnyard broad-leaf needle Number Ratio 2.5 leaves 3.5-leaves grass weeds spikerush stage stage [0 15 2 3 3 8 4 2.0 10 O 0 O 0 O i 30 5 0 0 O 0 Untreated 74 98 38 200 I00 In Table 4, the number of surviving broadleaf weeds EXAMPLE 4 is the summed number of surviving monochoria, toothcup, false pimpernel, flat-sedge and water starwort.

The injury against rice was also rated on a scale as defined below.

No injury 35 Extremely slight injury Slight injury -l-l- Medium injury -ll 'l' Severe injury Test results are tabulated in Table 4.

The same compounds as used in the Example 65 In each of l/5,000 are Wagner pots was placed a given amount of alluvial paddy-field soil and fertilizers supplied in accordance with usual rice cultivation, to provide paddy field conditions usually found in paddy fields during rice plantation. Thereafter, the perennial of slender spike-rush were planted in a manner such that a particular number of buds might be present. The irrigation water was kept at the level of about 0.5 cm until germination of slender spikerush was observed and at the level of 3 cm after the germination. At 15th day from the plantation of the perennial of slender spikerush, the treatment of the pots was carried out using a regulant mixture of 3,3'-dimethyl-4- methoxybenzophenone (Compound No. 5) and Simetryne and a regulant mixture of Compound No. 5 and Prometryne. At 32nd day from the treatment, herbicidal effects of the regulant mixtures were examined. The results are shown in Tables 6 and 7.

Table 6 Herbicidal effects of a regulant mixture of Compound No. 5 and Simetryne Herbicidal effects of a regulant mixture of Compound No. 5 and Prometryne Dose (g/a) of Herbicidal effect on Dose (g/a) of Compound No. 5 Prometryne slender spikerush Remarks:

1) Ratings of herbicidal effect are defined in terms of the following numerals:

: Completely (100%) killed 4: X051 killed t): No herbicidal effect (The same number of weeds as in untreated areas sun-bed.)

The following examples illustrate the methods of manufacturing agricultural preparations suitable for practical use.

EXAMPLE 5 Emulsified preparation A homogeneous emulsion is obtained by mixing 20 parts of an active compound of the invention, 70 parts of a mixture containing equi-amounts of xylene, ben- Zene and dimethylformamide, and parts ofa mixture of an alkylphenol polyether alcohol and a calcijm alkylbenzenefulfonate.

EXAMPLE 6 Dust preparation 20 Parts of an active compound of the invention, 20

parts of a mixture of diatomaceous earth and finely divided powder of hydrated silicic acid and 60 parts of talc are mixed together and milled to disperse the active compound uniformly into the carrier materials and the resulting mixture is finely divided to give a dust preparation.

EXAMPLE 7 Wettable powder preparation 50 parts of an active compound of the invention are mixed with 30 parts of finely divided powder of hydrated silicic acid and 12 parts of clay, and then mixed homogeneously with 8 parts ofa mixture of sodium laurate and sodium dinaphthylmethanesulfonate. The mixture obtained is then milled into finely divided powder.

EXAMPLE 8 Granular preparation 2 Parts of an active compound of the invention are mixed with 35 parts of diatomaceous earth. 23 parts of bentonite, 38 parts of talc and parts of a suitable disintegrator. and the resulting mixture is uniformly wetted by adding 18 parts of water thereto and subjected to granulation by the aid of an extrusion molding machine. After applying the granules obtained to a dry crusher, the size of the granules is rendered uniform to give a granular preparation.

What is claimed is:

1. The method of combatting weeds comprising ap plying thereto an effective amount of one or more compounds of the general formula CO @R (1) wherein R is a lower alkyl gr oup or allyl group and R is a lower alkyl group, is used as the compound of the general formula (1).

3. The method of combatting weeds according to claim 1 wherein a compound of the general formula (1) is 3,3'-dimethyl-4-methoxybenzophenone. 

1. THE METHOD OF COMBATTING WEEDS COMPRISING APPLYING THERETO AN EFFECTIVE AMOUNT OF ONE OR MORE COMPOUNDS OF THE GENERAL FORMULA
 2. The method of combatting weeds aCcording to claim 1 wherein a compound of the general formula:
 3. The method of combatting weeds according to claim 1 wherein a compound of the general formula (1) is 3,3''-dimethyl-4-methoxybenzophenone. 